Commercial trucks often utilize a conventional collision warning system, such as the Eaton VORAD® EVT-300 Collision Warning System, to alert the driver that there is an obstacle in the path of the vehicle. This warning provides the driver with valuable time to steer the vehicle around the obstacle, thereby potentially avoiding a collision with the obstacle. Conventional collision warning systems typically utilize an antenna mounted to a bumper or chassis of a vehicle wherein the antenna is generally aligned with a centerline of the vehicle bumper. In operation, the antenna picks up and relays signals to the collision warning system when obstacles are detected in the direction of alignment of the antenna. However, if the antenna is slightly misaligned in a horizontal or vertical plane and thus oriented at an incorrect direction and pitch angle (i.e., the antenna is directed at a distant point away from the direction of travel of the vehicle), the collision warning system may properly alert drivers of obstacles a short distance from the vehicle but will not pick up obstacles further ahead in the path of the vehicle. Thus, in order for the collision warning system to be effective, it is particularly important that the antenna be properly aligned both horizontally along a thrust line or direction of travel of a vehicle and vertically (in pitch) a distance ahead along the thrust line or direction of travel of the vehicle, and not merely haphazardly positioned in a direction generally straight ahead of the vehicle.
As will be appreciated by those skilled in the art, optimal operation of a collision warning system requires the antenna to be properly aligned both horizontally and vertically at a desired pitch angle along a direction of travel of a vehicle. FIG. 10 illustrates that a horizontal component of a vehicle thrust line 86 may occasionally be offset from a vehicle centerline 88. This is because the vehicle thrust line 86 is determined by the direction or orientation of the axles of the vehicle while the vehicle centerline 88 is determined by the orientation of the body or frame of the vehicle. Thus, merely placing the antenna 70 along the centerline 88 of the vehicle and aligning it thereto does not necessarily align the antenna with the thrust line 86 of the vehicle 76.
By way of explanation, thrust angle is the line that divides the total angle of the rear wheels. The rear tires of a vehicle are not just following the front tires, they are actually establishing direction of the vehicle, and in doing so, a direction of thrust is developed. The thrust angle created by the rear wheels is used as a reference for aligning the front wheels. Ideally, the thrust angle should be identical to the geometric centerline of the vehicle. If the thrust angle and geometric centerline are identical, the position of the tires would then form an absolute rectangle and the front tires could be aligned to the rear tires, resulting in a perfectly centered steering wheel. Because of factory tolerances and a varying degree of damage and/or wear, it is increasingly unlikely that the axles will be parallel. When the rear axle projects a different angle than the front axle, the driver will need to turn the steering wheel to compensate in order to drive in a straight line. In such cases, alignment of the antenna 70 with the vehicle thrust line 86, rather than the vehicle centerline 88, will increase the accuracy and sensitivity of the collision warning system. Additionally, the vertical or pitch orientation of the antenna may need to be adjusted out of true vertical to insure that the antenna is directed according to the desired orientation (e.g., at the ground immediately in front of or a distance away from the vehicle rather than level straight ahead of the vehicle). Additionally, the thrust line for one vehicle may vary from that of another due to variations in wheel-base and vehicle design styles between different vehicle models, and may even vary among vehicles of the same design as a result of variations in construction such as wheel axle alignment, dimensions, and position, even where such variations are within acceptable tolerances. It has therefore been difficult in the past to determine a single fixed reference point for a vehicle thrust line which is repeatable for all vehicles. Many different methods or devices for determining a vehicle thrust line have been devised over the years to determine or measure the thrust line of a vehicle. Accordingly, when an alignment device is used to align an antenna for a vehicle collision warning system, or the like, it is preferably utilized in combination with a device or method which accurately establishes a thrust line 86 of a vehicle, or alternatively with a device or method for determining a desired horizontal and vertical (pitch) orientation.
Current alignment methods are laborious, multi-step processes, each step of which has the potential of incurring errors in alignment. When such errors are combined, the resulting overall error can be significant. According to one current method, an operator first loosely mounts an antenna to the vehicle bumper along a center line of the vehicle. The operator then checks for vertical alignment (up or down) of the antenna by placing a level along a side of the antenna until the level indicates that the antenna has been properly vertically aligned in pitch. Following this, the operator removes the level and, while attempting to maintain the position of the antenna in the vertical alignment, secures the antenna to the bumper with securing screws or other fasteners. While attempting to maintain the vertical alignment, the operator then must adjust the antenna horizontally with respect to the thrust line of the vehicle. This horizontal adjustment requires loosening the antenna from the bumper, thereby potentially affecting the vertical alignment. Currently, horizontal alignment (left and right) of the antenna is accomplished by identifying two reference points symmetrical about the truck centerline and using a six foot straight edge clamped to the vehicle to connect the two points. Unfortunately, the tortuous shape of the vehicle bumper makes clamping a long straight edge difficult and imprecise. Further, clamping potentially distorts the shape of the bumper or deflects the shape of a plastic housing to a degree which skews the measurement. Moreover, this method generally is able to align the antenna horizontally only with respect to the centerline of the vehicle and does not insure that the antenna will be aligned both horizontally and vertically along the thrust line of the vehicle. In addition, in order to adjust the antenna into proper horizontal alignment, the antenna must be unsecured from the previously established vertical alignment position. Once the securing screws are loosened, it is difficult to precisely and delicately control the movement of the antenna in the horizontal plane without also affecting the vertical alignment. Thus, misalignment in either or both planes is common.
A need therefore arises for an alignment device and method of using the same which allows a single technician to quickly and easily secure an object substantially in a desired horizontal and vertical orientation with respect to a fixture in a manner that further ensures that both horizontal and vertical alignment are achieved and preserved when the object is secured to the fixture.
It would also be desirable to have an alignment device and method of using the same which, following alignment, maintains the object substantially in the desired horizontal and vertical orientation even when the technician is not physically supporting the alignment device, such as while the technician is securing the object to the fixture.
More particularly, what is needed for a particular application is an antenna alignment device and a method for using the device which allows for quick, easy, and reliable horizontal and vertical alignment of a vehicle mounted antenna by a single technician such that the antenna is aligned both vertically and horizontally along a thrust line of a vehicle.
Additionally, what is needed is an alignment device that can be successfully employed with any device or method for determining a thrust line of a vehicle or any other desired alignment orientation.